Answer:
C. necessary to abolish slavery nationwide forever
Step-by-step explanation:
It abolished any sort of forced/involuntary servitude with one exception only, in case of someone being condemned for a crime.
The 13 Amendment says that: "either slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction".